Two Elements have similar Characteristics
Two elements have similar characteristics when they relate to the same family which indicates that they have placed in the same group in the periodic table. There are only those elements which have same properties that are present in the same group. This is because there are same properties along the same group.
Their valency also remains same along the same group. For instance, sodium (Na) and lithium (Li) are present in the same group. They have same valency which is 1 and other properties as well. Good example are electronegativity, density, melting point, boiling point, and many other features.